Organo-titanium catalysts for the preparation of polyesters



United States Patent ORGANO-TITANIUM CATALYSTS FOR THE PREP- ARATION OF POLYESTERS John R. Caldwell and John W. Wellman, Kingsport, Tenn., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application October 3, 1952, Serial No. 313,075

17 Claims. (Cl. 260-75) This invention relates to a process for preparing polyesters which comprises condensing a diester of a dicarboxylic acid with a polyhydroxy compound in the presence of at least one of a group of novel catalytic condensing agents which are titanium tetralkoxides and quaternary ammonium salts containing a complex titanium hexalkoxy radical and which are defined hereinbelow. These novel catalytic condensing agents can be advantageously employed in the preparation of linear polyesters wherein the dicarboxylic acid is an aromatic compound which does not contain any ethylenic (olefinic) unsaturation and the polyhydroxy compound is a dihydroxy compound. In preparing such linear polyesters it is advantageous to conduct the condensation in an inert atmosphere at an elevated temperature which is increased during the course of the condensation up to a temperature of from about 225 to about 310 C., the condensation being conducted during the latter stages thereof at a very low subatmos pheric pressure.

This application contains subject matter disclosed to some extent in a copending application, Serial No. 143,594, filed February 10, 1950, by J. R. Caldwell, now U. S. Patent No. 2,614,120, dated Qctober 14, 1952. This application also contains subject matter disclosed in other copending applications filed on even date herewith by J. R. Caldwell, Serial Nos. 313,061 through 313,071.

Various polyesters of dicarboxylic acids and polyhydroxy compounds are well known in the prior art and have been used, for example, in the manufacture of paints and varnishes. Moreover, prior art disclosures set forth various linear condensation polyesters derived from dihydroxy compounds and dibasic acids such as terephthalic acid which are capable of being drawn into fibers showing characteristic X-ray patterns, orientation along the fiber axis. However, many of these linear polyesters possess a relatively low melting point and a fairly considerable solubility in various solvents whereby they are of restricted utility, especially in the textile field. These polyesters vary considerably in their characteristics, depending on the particular dicarboxylic acid and the particular polyhydroxy compound employed. Generally speaking, these polyesters have various physical characteristics which are not as satisfactory as could be desired.

The preparation of polyesters is well known in the prior art and involves the reaction of a dibasic dicarboxylic acid with a dihydric or polyhydric alcohol. It is advantageous to employ esters of the dicarboxylic acid whereby ester interchange takes place with the glycol or polyhydric alcohol to form a polyester and an alcohol. When using the ester interchange method, the time required to form the polyesters is generally considerably less than when the free dicarboxylic acid is employed. The long chain in the polyester is built up by a series of ester interchange reactions wherein the glycol displaces a relatively lowboiling alcohol component of the acid ester to form a glycol ester. During the last stages of the reaction, it is generally desirable to heat the condensing reaction mixture to a temperature of about 225-275 C. or higher in order to maintain the fluid state. For this reason, the properties of the catalytic condensing agent are very important.

A desirable catalytic condensing agent must be active enough to promote ester interchange at a temperature below the boiling point of the glycol or other polyhydric alcohol. At the same time, the catalyst must be stable at temperatures of 225 -310 C. or even higher if necessary. Furthermore, the catalyst must not cause decomposition or degradation of the polyester at these high temperatures.

In accordance with this invention, it has been found that certain compounds are especially valuable for use as catalytic condensing agents in the preparation of high melting linear polyesters. They have the general formula structures set forth below:

wherein R represents an alkyl radical containing from 1 to 6 carbon atoms and R, R" and R each represents a member of the group consisting of an alkyl radical containing from 1 to 6 carbon atoms and an aryl radical of the benzene series containing from 6 to 9 carbon atoms.

These novel catalysts can be advantageously employed in processes for preparing polyesters, which processes are described below. These novel catalysts are efiective only when substantially anhydrous conditions are employed and no free acid is present to a suficiently significant extent to destroy the catalyst compound; thus, when free acids are employed the acids are first reacted with a hydroxy compound (preferably the polyhydroxy compound to be employed in the polyesterification process) before the novel catalyst of this invention is added.

Titanium tetralkoxides can be prepared by reacting titanium tetrachloride with an alcohol in the presence of an alkali metal alkoxide. Examples of suitable alcohols include methyl, ethyl, propyl, sec. butyl, n-amyl, sec. hexyl, and other alcohols containing from 1 to 6 carbon atoms. Examples of suitable alkali metal alkoxides include sodium ethoxide, potassium butoxide, lithium propoxide, etc. The titanium tetralkoxide formed by this process can be distilled at a greatly reduced pressure from the reaction mixture, e. g. at 5 mm. of Hg pressure or less. Thus, titanium tetrabutoxide can be formed by refluxing one gram mole of titanium tetrachloride, six gram moles of butyl alcohol and 0.5 gram moles of sodium butoxide. The titanium tetrabutoxide can then be distilled in vacuo to separate it from the reaction mixture.

Titanium tetralkoxides can also be prepared by reacting titanium tetrachloride with an excess of an appropriate alcohol in the presence of ammonia. ide can then be distilled in vacuo.

The preparation of the titanium tetralkoxides is described by Boyd, Journal of Polymer Science, 7, 596 (1951), wherein such compounds are prepared from titanium tetrachloride and various alkanols. Other methods of preparation can also be employed.

The preparation of the ammonium salts is not described in the literature since these are novel compounds.

The quaternary ammonium salts containing a complex titanium hexalkoxy radical can be prepared by reacting a quaternary ammonium hydroxide with a salt of titanium hexalkoxide (see the copending application filed on even date herewith by J. R. Caldwell, Serial No. 313,072) or by reacting with titanium tetralkoxide (see description for preparation above) and the corresponding alcohol in a non-aqueous reaction medium. Examples of suitable qua ternary ammonium hydroxides include tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide, tetrabutyl ammonium hydroxide, benzyltrimethyl am- The titanium allroxmonium hydroxide, benzyltriethyl ammonium hydroxide, tripropylphenyl ammonium hydroxide; dibenzyldi-n-arnyl ammonium hydroxide, etc. The non-aqueous media suitable for conducting reactions for preparingthese novel catalysts includefethyl alcohol, isopropyl alcohol, benzyl alcohol, ethyl ether, diphenyl ether, dioxane, etc. The preparation of these quaternary ammonium salts is advantageously conducted under refluxing conditions. The product obtained can be separated and purified by distillation in vacuo or used as a catalyst in solution in the reaction medium.

Examples A, .B and C, set forth below, describe and exemplify the preparation of various quaternary-ammonium salts containing the titanium hexalkoxy radical.

The novel catalysts of, thisinvention give a very rapid reaction rate at all stagesof the polyesterification process,

including the final step Where, the molecular weight is built up. They are particularly valuable for the preparation of high melting polyesters from 1,6-hexanediol and LS-pentanediol. It is well known that these glycols have a tendency to decompose at temperatures above 250-260" C. and hence are diilicult to use. With the novel catalysts described above polyester reactions employing these glycols can be carried out at temperatures up to 300 C. or

' even higher without excessive decomposition.

' to all of the polyesters described herein.

By employing the novel catalysts of this invention, the reaction rate of the polyesterification process can be increased by a factor which is generally from about 2' to 5 times the reaction rate obtainable when catalysts known in the prior art are employed. Moreover, the novel catalysts of this invention have the valuable characteristic of minimizing side reactions which have the tendency of causing considerable degradation of the polyester products at the relatively high temperatures employed in preparing highly polymeric polyesters. Furthermore, by employing these novel catalyststo increase the rate of condensation, the. time available'for possible decomposition of the high molecular weight polyester moleculesbeing formed at high temperatures is appreciably reduced. Thus, by increasing the reaction rate; the timerequired to make a polyester is reduced which is quite important-because at 2503300? C. the degree of color formation and extent-of deleterious side. reactions is proportional to the time of heating.

The polyesters produced when-employing these novel catalysts have greatly improved properties as'compared to products obtained employing catalysts known in the prior art.. The. molecular weight is considerably higher whereby highly polymeric polyesters are obtained. The color of the polyesters obtained is excellent; the products "can therefore be. employed for purposes calling for 'white or colorless materials. The physical properties of the polyesters obtained are. also superior. At hightemperatures' there is a great improvement in the-inherent viscosities' of linear polyesters which are suitable for melt spinning or extrusion whereby fibers, films, etc. can be produced having propertiessuperior to those obtainable with known catalysts.

The herein described novel catalysts are especially valuable for the preparation of polyesters employing diesters of p,p'-sulfonyl dibenzoic acid. as described in copending applications filed. oneven date-.herewithby J. R. Caldwell, Serial Nos. 313,061-313,068.

Many of. thesepolyesters are very high melting and the reaction must often be carriedv out at a temperature of 280 -300 C. or higher. It has been foundthatrelatively few catalysts. are etfective' at this temperatureother than those described inthis application.

It is an object of this invention to provide new and improved catalytic condensing agents for promoting the formation of improved polyesters in processes involving ester interchange and alcoholysis. A further object of this invention is to provide a new and improved method for the preparation of polyesters wherein such new and improved catalysts are employed. Other objects will become apparent elsewhere in this specification.

A broad aspect of this invention relates to a process for preparing a polyester which comprises condensing under substantially anhydrous conditions at an elevated temperature in an inert atmosphere at diester of a dicarboxylic acid with from about .l to: about 10'equivalent proportions of a polyhydroxy compound, in the presence of a catalytic condensing agent selected from the group consisting of those compounds having the formulas:

wherein R, R, R" and R' are defined hereinabove.

' More specifically, this invention relates to a process for preparing a polyester comprising (A) condensingunder substantially anhydrous conditions an aromatic dicarbox'ylic acid diester having the formula:

wherein R1 and R4 each represents a substituent selected from the group consisting of an 'alkyl radical containing from 1 to 10 carbon atoms and an omega-hydroxyalkyl radical containing from 2 to 12 carbon atoms, R2 and R3 each represents (CH2)n-1Wh816ln n is a positive integer of from 1 to 5' inclusive and X represents a divalent aromatic radical selected from the group having the followand wherein Y represents a.divalent.radical selected from the group consisting of wherein m is a positive integer. of from 1 to 5 inclusive, (B) with an alpha, omega-dioxy compound selected from the group consisting oftthose compounds having the following'formulas:

employed in such a proportion that there is at least an equivalent amount of alpha and omega oxy substituents in proportion to the carbalkoxy substituents in the overall combination of the aromatic diesters and the alpha, omega-dioxy compounds, (C) in the presence of a condensing agent selected from the group consisting of the novel catalysts set forth above, (D) at an elevated temperature which is increased gradually during the course of the condensation up to a temperature of from about 225 to about 310 C., (E) the condensation being conducted in an inert atmosphere, (F) and conducting the condensation at a very low presure of the inert atmosphere during the latter part of the condensation.

Advantageously, the condensing agent is employed in an amount of from about 0.005% to about 0.2% based on the Weight of the aromatic dicarboxylic acid diester. Higher and lower proportions can also be employed.

Advantageously, the alpha, omega-dioxy compound is employed in such a proportion that there are from about 1.2 to about 3 alpha and omega oXy substituents in proportion to the carbalkoxy substituents in the overall combination of the aromatic diesters and the alpha, omegadioxy compounds. Higher (e. g. 10) and lower (e. g. 1) proportions can also be employed.

Since the alpha, omega-dioxy compounds which can be employed in accordance with this invention are most advantageously alpha, omega-dihydroxy compounds and in order to facilitate the phraseology which is employed in this specification, such compounds will hereinafter be referred to as polyhydroxy or dihydroxy compounds although it is to be understood that the alpha, omega-dioxy compounds of the type described above are intended to be covered by the term dihydroxy compounds or the term polyhydroxy compounds as such terms are employed herein.

Advantageously, the temperature employed during the earlier part of the condensation is from about 150 to about 220 C. Higher and lower temperatures can also be employed.

Advantageously, the low pressure defined under (F) is less than about nun. of Hg pressure (preferably less than 5 mm.). However, somewhat higher pressures can also be employed.

Most advantageously, the aromatic dicarboxylic acid diester is a diester of p,p-sulfonyl dibenzoic acid or terephthalic acid and the polyhydroxy compound is a polyrnethylene glycol.

This invention also includes processes as described above whereby polyesters can be prepared by replacing a part of the described aromatic dibasic acid diester with an ester of a replacement acid which can be an aliphatic dibasic acid, e. g. carbonic acid, oxalic acid, succinic acid,

adipic acid, sebacic acid, a,a-dimethylglutaric acid, di-.

in conjunction with the aromatic dibasic acid esters except when they are unsaturated and tend to form insoluble and infusible products due to cross-linkage effects, in which event the process described hereinabove is advantageously terminated at an intermediate temperature of about 250 C. before the pressure is reduced whereby products are obtained which can be called soluble intermediate polyesters which are useful in preparing protective coatings. The various polyesters containing replacement acid esters as described in this paragraph can be prepared according.

to procedures similar to those described in copending applications filed on even date herewith by J. R. Caldwell, Serial Nos. 313,062-313,066.

Polyesters can also be prepared in accordance with this invention by replacing a part of the described dihydroxy compound with what can be called a polyhydroxy compound which contains 3 or more hydroxy radicals, e. g. glycerol, sorbitol, pentaerythritol, dipentaerythritol, B-methylglycerol, 2 methyl-Z-hydroxymethyl 1,3 propanediol, 1,2,4-trihydroxybutane, etc. In the preparation of polyesters employing these polyhydroxy compounds, the reaction mixture is not generally heated to the high temperatures under reduced presure as described hereinabove since the product would become insoluble and infusible due to cross-linking of the molecules; hence, the process is halted at about 250 C. or less prior to the reduction in pressure of the inert atmosphere. Various solutions can then be prepared from these soluble polyester products which can then be cast into films or otherwise used in protective coating compositions. in preparing such soluble polyesters it is generally advantageous to employ an unsaturated aliphatic dibasic acid diester in lieu of a part of the described aromatic dibasic acid diesters, e. g. maleic, fumaric and itaconic diesters. The various polyesters containing replacement polyhydroxy compounds as described in this paragraph can be prepared according to procedures similar to those described in a copending applica tion filed on even date herewith by J. R. Caldwell, Serial No. 313,069.

The dihydroxy or polyhydroxy compounds defined above may not actually contain any free hydroxy radicals since they may be in esterified form as indicated by the formulas of the dihydroxy compounds set forth above. However, these hydroxy or substituted hydroxy radicals are referred to generally as hydroxy radicals or substituents. Each diester is considered as containing two carbalkoxy radicals as that term is employed in the definition of the process as described above since R1 and R4 may be alkyl radicals, or omega-hydroxyalkyl radicals. Even when the process is preceded by the preliminary step described below employing free acids, the term carbalk-oxy radicals in the description of the process is intended to encompass such free carboxy radicals.

Furthermore, this invention covers processes as defined above wherein the aromatic dicarboxylic acid diester is formed by a preliminary step comprising condensing an aromatic dicarboxylic acid having the formula:

(wherein R2, R3 and X are defined under (A) in the abovedescribed process), with a polyhydroxy compound which is defined above under (B) and is employed in the pro portions set forth under (B), at an elevated temperature, after which preliminary step the novel catalytic condensing agent which is defined under (C) is added and the condensation is completed as defined under (D), (E) and (F). Advantageously, the elevated temperature employed during the preliminary step is substantially that at which reflux conditions subsist; however, higher and lower temperatures can also be used. Advantageously, as indicated hereinbefore, the polyhydroxy compound is employed in such a proportion that there are from about 1.2 to about 3 hydroxy substituents in proportion to the acid substituents in the overall combination of the aro matic diester and the polyhydroxy compound.

In preparing polyesters, especially linear highly polymeric polyesters, it is important to exclude oxygen and moisture at all stages of the condensation, particularly during the latter stages thereof. An inert atmosphere is employed to exclude oxygen; such atmospheres include hydrogen, nitrogen, helium, etc. The reacting materials employed in the condensation are advantageously substantially anhydrous; however, if water is initially present or is formed during the course of the condensation, it can be substantially completely removed prior to the final stages of the condensation by operating in accordance with the specified process or otherwise.

Examples of aromatic dicarboxylic acid diesters which can be employed as defined'above under -'(A)-' include the B-hydroxy-ethyl 'diester' of -p,p'-'sulfonyl. dibenzoic acid, P,PT-Sulfnyl .dibenzoic acid dibutyl ester, m,p'-sulfonyl dibenzoic acid dipropyl' ester, m,m'-sulfonyl dibenzoic acid dihexyl' ester, methyl terephthalate, hexyl terephthalate, isopropyl'terephthalate, as well asvarious esters having the following formulas:

l C O'-O Cal-Ir '-C6H130-OC GHrO- CH (JO-005E canto-oi: oo-oogn.

o CHr-(iF-CHz I GOO (ED-005E C3H O-OC CO-O 0 11 CsH10-O C" 0 (30-0 C3117 onto-0o s-wrnn-s o 0-0 on;

GzHgO-OC CO-OCaHs SOS The .dihydroxy compounds which canbe. employed to form highly polymeric linear polyesters are straight-chain alkane diols, viz. polymethylene glycols, wherein the hydroxy radicals are positioned at the two ends of the alkylene chain. Examples of such glycols include ethylene glycol, 1,3-propylene glycol, l,4butylene glycol, 1,6- hexylene glycol, 1,10-decamethylene. glycol, 1,12-dodecamethylene glycol, etc. As indicated. above,.mono or diesters of these. glycols. can also. be. employed. Thus, the acetates, propionates and butyrates are examples of such estersi The defined ether glycols can be employed either in lieu of the polymethylene glycols or in conjunction therewith as.modifiers. Examplesof ether glycols..in-

CHzO-OC -'C 0-0011:

et cetera.

clude' diethyleneglycol, triethylene glycol, tetraethylenev glycol, 1 bis (4-hydroitybutyl)- ether; --bis( 3-hydroxypropy1) ether, etc.

"Valuable fibers can-be advantageously'prepared employing the higher melting polyesters which can be produced according to theprocedures describedherein. Preferably noaliphatic ether glycol is employed when fibers are to be prepared. Furthermore, the aromatic aciddiesters-should ordinarily contain only p,p' linkages when highly polymericlinear polyesters are desired. However, on the other hand, valuable polyesters can be prepared employing aliphatic ether glycols without any polymethylene glycol although the product obtained will not be suitable for forming useful fibers. The same applies to the employment'of aromatic diesters containing linkages in other than the para positions.

The catalytic condensing agents which can be employed have been described above. From about 0.005% to about 0.2% of such catalysts-based onthe weight of the diesters being condensed can be employed. Higher-or lower percentages can also be employed. Generally, from about 0.01% to about 0.06% of the catalytic condensing agent can be advantageously employed based on the Weight of the various diesters being condensed.

The temperature at which polyesterific'ation canbe conducted is dependent upon the specific reactants involved in any given reaction. In general, the reaction mixture can be heated with agitation at from about 150 to about 220 C. for from approximately one to three hours in an inert atmosphere (e. gjnitrogen or hydrogen); the mixture can then be heated with agitation at from about 225 -'24(}' to about 280 310 C. in the same atmosphere for approximately 1 to 2 hours. Finally, the pressure can be greatly reduced to form a vacuum (less than about 15 mm. of'I-Ig pressure but preferably on the order of less than 5 mm. of Hg pressure) while the temperature is maintained in the same range (225-310 (3.); these conditions are advantageously maintained for approximately 1 to 6 additional hours. This final phase is advantageously carried out With good agitation under the high vacuum in order to facilitate the escape of volatile products from the highly viscous-melt. The conditions can be'varied' considerably'depending upon the degree of polyesterification desired, the ultimate properties'sought, the

. stability of the polyester being produced, and the use for ester fiber is placed on the'fiat surface of a heated bar and a" Weight. of grams is applied to the fiber along a distance'ofp ys inch of the fiber length. The contact surface 'of this Weight has a coating of polytetrafluoroethylene which acts as a thermal insulator. The fiber is allowed'to' remainin contact with the bar under this weight foroneminute. The minimum temperature at which the fiber adheres to the hot bar under these conditions is the sticking temperature as that term is employed in theexamples' given herein.

This invention can he further illustrated by the following examples; in addition to these examples it is apparent that other variations and modifications thereof can be adapted to obtain similar results:

-, Example 1.--Ti(O4H9)4 as the catalyst "Eightyfour g. (0.2 mol) of p,p'-sulfonyl dibenzoic acid butyl'ester and 36 g. (0.3 mol) of 1,6-hexanediol were'placed in avessel equipped with a variable speed stirrer'of the anchor'type, a short distillation column, and

butyl alcohol containing 0.1 g. of titanium tetrabutylate,

Ti(OCtH9)4, was added. The mixture was heated in a metal bath at 200-210 C. and stirred at 100-120 R. P. M. While pure hydrogen was passed over the surface. Butyl alcohol distilled off rapidly and the ester interchange was practically complete in 30 minutes. The temperature was then raised to 270-280 in 15 minutes and heating was continued for 10-15 minutes. Some of the excess glycol distilled ofi at this stage. The hydrogen gas was shut off and a vacuum of about 1 mm. Hg pressure was applied. The melt rapidly increased in viscosity and in about 15 minutes it was necessary to reduce the stirrer speed to 40 R. P. M. As the viscosity increased the stirrer speed was gradually reduced. After a total time of 30-40 minutes under vacuum, the melt had become too viscous to stir and the reaction was stopped. The melt obtained was clear and colorless. After cooling slowly the product was hard and opaque due to crystallinity. If the melt is suddenly cooled or quenched, it has a tendency to remain amorphous and transparent. On a hot stage, in polarized light, the crystalline material shows a melting point of 270-280 C. The inherent viscosity in 60% phenol- 40% tetrachlorethane is 0.70-0.80. Fibers can be pulled from the melt and cold-drawn SOD-600%. They stick on a hot bar at 230-240 C. The polyester also gives valuable sheets and films. 1

Example 2.Ti(OC2H5):x as the catalyst One hundred g. p,p'-sulfonyl dibenzoic acid ethyl ester and 40 g. 1,5-pentanediol were placed in a reaction vessel equipped with a stirrer, a short distillation column, and an inlet tube for purified nitrogen. Five cc. of ethanol containing 0.4 g. Ti(OC2H5)4 was added and the mixture was heated at l80-200 C. with stirring. After 1 hour, the distillation of ethyl alcohol ceased, and the temperature was raised to 280-3? C. where it was held for 20 minutes. A vacuum of 0.5 to 1.0 mm. was applied for 1 hour, while the temperature was maintained at 280-285 C. A colorless product having an inherent viscosity of 0.80-0.90 in 60% phenol-40% tetrachlorethane solution was obtained. Fibers pulled from the melt and cold-drawn 400-500% show a sticking temperature of 240-250" C. The product is also useful for films and sheets.

Example 3.-Ti(OCsH7)4 as the catalyst One gram mol of methyl sebacate, 4 gram mols of p,p'-sulfonyl dibenzoic acid, butyl ester, and 7 gram mols 1,6-hexanediol were placed in a vessel as described in Example 2. Five-hundredths per cent Ti(OC3Hr)4 was added, based on the weight of the two esters. A heating schedule similar to that given in Example 2 was followed. The product obtained is very tough and rubbery. It has an inherent viscosity of 0.80 in a solvent of 60% phenol- 40% tetrachlorethane. Fibers pulled from the melt show a rubbery elastic elongation of 30-40%. This product is also useful as a molding plastic.

Example 4.Ti(OC4H9)4 as the catalyst One gram mol of methyl isphthalate, gram mols of p,p'sulfonyl dibenzoic acid ethyl ester, and 10 gram mols 1,5-pentanediol were placed in a vessel as described in Example 2. Six-hundredths per cent Ti(OC4H9)4 was added, based on the weight of the two esters. A heating schedule similar to that given in Example 2 was followed. The product obtained is hard and crystalline. It is useful for injection molding.

Example 5.-Ti(OCzH5)4 as the catalyst One hundred g. methyl terephthalate and 40 g. ethylene glycol were placed in a vessel as described in Example 1. Three-hundredths per cent Ti(OC2H5)4 was added, based on the weight of methyl terephthalate. A heating schedule was followed as described in Example 1. A polyester having excellent color and an inherent viscosity of 0.80-0.90 was obtained.

Example 6.-Ti(OC5H11) as the catalyst The polyester described in Example 5 was again prepared employing the same apparatus and procedure except for the substitution of 0.03% of Ti(OC5H11)4 as the catalyst. A polyester was obtained having the same properties as that described in Example 5.

Example 7.Ti(OC4H9)4 as the catalyst One gram mole of p,p-dicarbethoxydiphenyl methane and 2.1 gram moles of ethylene glycol were condensed in apparatus as described in Example 1 according to the procedure set forth therein employing 2 cc. of the same catalyst solution. The product obtained was a highly polymeric linear polyester useful as a molding resin, for preparing films, sheets, etc.

Example 8.Ti(OC4H9)4 as the catalyst One gram mole of p,p-dicarbomethoxybenzophenone and 2.4 gram moles of trimethylene glycol were condensed in apparatus as described in Example 1 according to the procedure set forth therein employing 2 cc. of the same catalyst solution. The product obtained was a highly polymeric linear polyester useful as a molding resin, for preparing films, sheets, etc.

Example 9.-Ti(OC4H9)4 as the catalyst One gram mole of 1,2-bis(p-carbopropoxyphenyloxy) ethane and 2.5 gram moles of ethylene glycol were condensed in apparatus as described in Example 1 according to the procedure set forth therein employing 2 cc. of the same catalyst solution. The product obtained was a highly polymeric linear polyester useful as a molding resin, for preparing films, sheets, etc.

Example 10.( (CH3 4N) H (Ti( OC4H9) s) as the catalyst Eighty-four grams (0.2 mol) of p,p'-sulfonyl dibenzoic acid butyl ester and 36 g. (0.3 mol) of 1,6-hexanediol were placed in a vessel equipped with a variable speed stirrer of the anchor type, a short distillation column, and a gas inlet tube for purified hydrogen. Two cc. of n-butyl alcohol containing 0.1 g. of

was added. The mixture was heated in a metal bath at ZOO-210 C. and stirred at -120 R. P. M. while pure hydrogen was passed over the surface. Butyl alcohol distilled off rapidly and the ester interchange was practically complete in 30 minutes. The temperature was then raised to 270-280 in 15 minutes, and heating continued for 10-15 minutes. Some of the excess glycol distilled olf at this stage. The hydrogen gas was shut off, and a vacuum of about 1 mm. was applied. The melt rapidly increased in viscosity, and in about 15 minutes it was necessary to reduce the stirrer speed to 40 R. P. M. As the viscosity increased, the stirrer speed was gradually reduced. After a total time of 30-40 minutes under vacuum, the melt had become too viscous to stir and the reaction was stopped. The melt was clear and colorless. After cooling slowly, the product obtained is hard and opaque due to crystallinity. If the melt is suddenly cooled or quenched, it has a tendency to remain amorphous and transparent. On a hot stage, in polarized light, the crystalline material shows a melting point of 270-280" C. The inherent viscosity in 60% phenol-40% tetrachlorethane is 0.70-0.80. Fibers can be pulled from the melt and cold-drawn 500600%. They stick on a hot bar at 230-240 C. The polyester also gives valuable sheets and films.

Example 11 (CzHs) 4N) H(Ti (OCzHs s) as the catalyst One hundred grams p,p'-sulfony1 dibenzoic acid ethyl ester and 40 g. 1,5-pentanediol were placed in a reaction vesselequipped with a stirrer, a short distillation aye-ass:

, 11 column, and an inlet tube for purified nitrogen. Five cc..or" ethanol containing 0.4 g. of

((C2H5)4N)H(T1'(OC2H5)6) was added, and the mixture heated at 180-200 C. with stirring. After-one-hour, the. distillation of ethyl alcohol ceased, and the temperature was raised to 280-285 C. where it was held for 20 minutes. A vacuum of 0.5 to 1.0 mm; was applied for one: hour, while the temperature was maintained at 280-285 C. A colorless product having aninherentviscosity of 0.80-0.90 in 60% 'phenolf40% .tetra'chlorethane solution :was obtained. Fibers pulled from. the. melt :and cold-drawn 400'500%. show a sticking temperature of, 240-250 C. The product is alsonsefulrfor films. andsheets.

Example 12.( (CH3)3(C6H5CH2)N)H(Ti(CC4H9)5) as the catalyst One gramhmol of: methylsebacate, 4 gramv mols of p,p-sulfonyl dibenzoic. acid, butyl ester,- and 7. gram mols l,6-hexanediol' were placed in a vessel. as described in Example 10.. Fivc-hundredths .per. cent CH3 acemcnnmmruocunn was added, based on the weight of the two esters. A heating schedule similar to that given in' Example was followed. The product obtained is very tough and rubbery. It has an inherent viscosity of 0.80 in a solvent of 60% phenol-40% tetrachlorethane. Fibers pulled from the melt show a-rubbery elastic elongation of 30-40%. This product is also .useful as a molding plastic.

Example 14.-.((C3H7)4N)H(Ti(OCH3)e).ias the catalyst One hundred gramsmethyl terephthalate and 40 g. ethylene glycol were placed in a vessel as described in Example 10. Three-hundredths percent was added, based .on the weight of methyl-terephthalate. A heating schedule was followed as described in Example 10. A polyester having' excellent color andan inherent viscosity of 0.80-0.90 was obtained.

One gram mole of p,p-' -dicarbethoxydiphenyl: methane and 2.1 grams moles of ethylene. glycol werecondensed in apparatus as describedin Example 10' according to the procedure set forth therein employing 2 cc..of-.the same catalyst solution. The product .obtained was a.highly polymeric linear polyesterusefu-las a molding resin, for preparing films,.sheets, etc.

One gram mole of p,p'-dicarbomethoxybenzophenone and 2.4 gram moles of trimethylene glycol were condensed in apparatus as described in Example 10 according-tothe procedure set forth therein employing 2 cc. of the same catalyst solution' The product obtained was a highly polymeric linear polyester'useful as a molding resin, for preparing films, sheets, etc.

Example '17.-((CH3)sN2)H(Tl(OC4H9)6) One gram moleof 1-,2-bis (p-carboprop'oxyphenyloxy) ethane and 2.5 gram moles of ethylene glycol were condens'ed in apparatus as described in Example 10 according to the procedure set forth therein employing 2 cc. of the same catalyst solution. The product obtained was a highly polymeric'linear polyester useful as a molding resin, for preparing films, sheets, etc.

.1 Polyesters similar to those described in the above examples can be prepared employing 1,4-bis (p-carbamyloxyphenoxy)benzene, bis(p-carbethoxyphenyl)sulfide, N,N- bis(p-carbohexoxyphenyDmethylamine and p,p-dicarbethoxybiphenyl condensed with ethylene glycol, tetramethylene glycol and hexamethylene glycol.

In the. various formulas given for the catalysts in the above examples, C4H9 and the formulas for other such alkyl radicals are intended to represent the straight chain alkyl radicals. However, branched chain radicals can also be employed.

Theneutral and acidic quaternary ammonium salts of hexalkoxy titanium are novel compounds having the valuable usefulness described and exemplified hereinbefore. These compoundscan be prepared by the methods outlined above a'ud' can also be prepared by reacting quaternary ammonium'halides. or alkoxides with an alkali metal salt of an alkyl titanium compound.

The following exampleswill serve to further illustrate the preparation of these novel compounds:

...Example A.Trimethyl benzyl ammonium titanium hexabutoxide Ti(-OC'4H9)4 was prepared according to the method disclosed by'Boyd, J. Polymer Sci. 7, 596 1951). One gram molecular weight of trimethyl benzyl ammonium hydroxide was dissolved in 1 gram mole of Ti(OC4H9)4 dissolved in three times its weight of anhydrous butyl alcohol. The resultant solution contained:

This solution was employed as the catalyst in Example 12.

- When two gram moles of trimethyl benzyl ammonium hydroxide were employed in the process of Example A the product obtainedwas:

Example B-.'-Tetramethyl ammonium titanium hexabutoxide One: gram mole of tetrarnethyl' ammonium bromide was added to a solutionin an excess of butyl alcohol containing one gram .mole of NaHCIi(OC4H9)s) which is refer-red to in a copendingapplication filed by I. R. Caldwell on even date herewith, Serial No. 313,072. 7 The reaction which took place resulted in the production of plus sodium bromide which was filtered off. The desired product remained in solution. This solution was employed as the catalyst in Example 10.

Example C.-Tetraethyl ammonium titanium hexaethoxide R1000 coon.

wherein R1 and R4 each represents a-substituent selected from the group consisting of an alkyl radical containing from 1 to 10 carbon atoms and an omega-hydroxyalkyl radical containing from 2 to 12 carbon atoms and each of the substituents R1OOC- and COOR4 are located in a position not occupied by the -SO2 group, (B) with an alpha,omega-dioxy compound comprising a compound selected from the group consisting of those compounds having the following formulas:

wherein p represents a positive integer of from 2 to 12 inclusive, R5 and Rs each represents a substituent selected from the group consisting of a hydrogen atom and an acyl radical containing from 2 to 4 carbon atoms, R7 represents an alkylene radical containing from 2 to 4 carbon atoms and q represents a positive integer of from 1 to 10 inclusive, the alpha,omega-dioxy compound being employed in such a proportion that there is at least an equivalent amount of alpha and omega oxy substituents in proportion to the carbalkoxy substituents in the overall combination of the aromatic diester and the alpha,omega-dioxy compound, (C) in the presence of a catalytic condensing agent selected from the group consisting of compounds having the following formulas:

wherein R represents an alkyl radical containing from 1 to 6 carbon atoms and R, R and R each represents a member of the group consisting of an alkyl radical containing from 1 to 6 carbon atoms and an aryl radical of the benzene series containing from 6 to 9 carbon atoms, (D) at an elevated temperature which is increased gradually during the course of the condensation up to a temperature of from about 225 to about 310 C., (E) the condensation being conducted in an inert atmosphere, (F) and conducting the condensation at a very low pressure of the inert atmosphere during the latter part of the condensation.

2. A process as defined in claim 1 wherein the condensing agent is employed in an amount of from about 0.005% to about 0.2% based on the weight of the aromatic dicarboxylic acid diester.

3. A process as defined in claim 2 wherein the alpha, omega-dioxy compound is employed in such a proportion that there are from about 1.2 to about 3 alpha and omega oxy substituents in proportion to the carbalkoxy substituents in the overall combination of the aromatic diester and the alpha, omega-dioxy compound.

4. A process as defined in claim 3 wherein the elevated temperature employed during the earlier part of the condensation is from about 150 C. to about 220 C.

5. A process as defined in claim 4 wherein the low pressure defined under (F) is less than mm. of Hg pressure.

6. A process as defined in claim 5 wherein the low pressure defined under (F) is less than 5 mm. of Hg pressure.

7. A process as defined in claim 6 wherein the aromatic diester is derived from p,p-sulfony1 dibenzoic acid and the condensing agent is Ti(OC4H9)4.

8. A process as defined in claim 6 wherein the aromatic diester is derived from p,p'-sulfonyl dibenzoic acid and the condensing agent is ((CHs)4N)H(Ti(OC4H9)s).

9. A process as defined in claim 6 wherein the aromatic diester is derived from p,p'-sulfony1 dibenzoic acid and the condensing agent is 10. A quaternary ammonium salt containing a complex titanium hexalkoxy radical having a formula selected from the group consisting of those consisting of wherein R represents an alkyl radical containing from 1 to 6 carbon atoms and R, R" and R' each represents a member of the group consisting of an alkyl radical containing from 1 to 6 carbon atoms and an aryl radical of the benzene series containing from 6 to 9 carbon atoms.

11. A process for preparing a quaternary ammonium salt containing a complex titanium hexalkoxy radical comprising reacting a quaternary ammonium hydroxide having the formula:

wherein R represents an alkyl radical containing from 1 to 6 carbon atoms and R, R" and R' each represents a member of the group consisting of an alkyl radical containing from 1 to 6 carbon atoms and an aryl radical of the benzene series containing from 6 to 9 carbon atoms with a titanium tetra-alkoxide having the formula:

wherein R is defined above, this reaction being conducted in the presence of an excess of an alcohol corresponding to the tetraalkoxide.

12. A quaternary ammonium salt as defined in claim 10 having the following formula:

((CH3)4N)H(Ti(OC4H9)s) 13. A quaternary ammonium salt as defined in claim 10 having the following formula:

((CH3)3(C6H5CH2)N)z(Ti(OC4H9)s) 14. A quaternary ammonium salt as defined in claim 10 having the following formula:

15. A process as defined in claim 11 comprising reacting a compound having the formula (CH3)4NOH with titanium tetrabutoxide.

16. A process as defined in claim 11 comprising reacting a compound having the formula with titanium tetrabutoxide.

17. A process as defined in claim 11 comprising reacting a compound having the formula (CaHr) 4NOH with titanium tetramethoxide.

References Cited in the file of this patent UNITED STATES PATENTS Whinfield et al. Mar. 22, 1949 Caldwell Oct. 14, 1952.

OTHER REFERENCES 

1. A PROCESS FOR PREPARING A POLYESTER COMPRISING (A) CONDENSING UNDER SUBSTANTIALLY ANHYDROUS CONDITIONS AN AROMATIC DICARBOXYLIC ACID DIESTER HAVING THE FORMULA: 